1. Field of the Invention
The present invention relates to internal combustion engines equipped with a supercharger for supplying air under pressure to the intake manifold and more particularly to a waste gate communicating with the engine exhaust gases and responsive to intake manifold pressure for preventing excess intake manifold pressure above a desired maximum.
In a supercharged gasolene engine, such as used on automobiles and motorcycles, the supercharger will usually include a compressor impeller on one end of a shaft with a radial inward flow turbine wheel at the other end. Air fuel mixture enters the compressor and is compressed and passed to the engine intake manifold and then to the combustion chambers. When the exhaust gases leave the combustion chambers and flow through the exhaust manifold and exhaust pipe they are increased to a considerably higher volume and temperature and rotate the turbine wheel for operating the compressor. The greater volume of gas passing through the turbine wheel than through the compressor results in useful work obtained from the system and the air fuel mixture being passed into the cylinders at a pressure higher than atmospheric. Thus, more pounds of air can be delivered to the engine as compared to one which is naturally aspirated resulting in greater efficiency of fuel burned and greater power obtained from the engine. However, at higher engine speeds a supercharger will supply excessive higher temperature air fuel mixture to the intake manifold resulting in higher exhaust back pressure which reduces fuel economy without increasing engine power output.
This invention prevents the intake manifold pressure exceeding a predetermined value by venting excess exhaust gas back pressure, above a desired maximum, upstream with respect to the supercharger.
2. Description of the Prior Art
Prior patents, such as U.S. Pat. Nos. 3,035,408 and 3,365,878, generally disclose waste gate controls which feature a perforated diaphragm connected with and opening and closing a valve to release or contain exhaust gas pressure driving a supercharger.
The principal disadvantage of this type waste gate control is the perforated diaphragm which has a relatively short life when compared with an imperforate diaphragm and further the control apparatus is bulky and for this reason is objectionable when attached to a relatively small engine, such as a motorcycle.
This invention provides a waste gate which features an imperforate diaphragm arranged in a plane parallel with the stem of the valve controlling exhaust gas pressure and has an overall low profile and when attached to a small engine, such as a motorcycle, does not materially increase the overall dimensions thereof.